Excision Repair by the Uvr System: Difference between revisions
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==General Description== | ==General Description== | ||
UvrA and UvrB are the first of four enzymes that assist in excision repair, and are both responsible for first scanning DNA for distortions. Once a genome distortion, such as those caused by a thymine dimer or another chemical adduct on a base, is detected by UvrA, UvrA leaves and UvrB proceeds to melt the DNA, creating a bubble around the lesion. UvrB then recruits UvrC. UvrC cleaves the area of the bubble, including the lesion, creating a short, single-stranded DNA segment that is then removed by DNA helicase, UvrD. The gap which results from the excision is filled by DNA polymerase and DNA ligase using the undamaged strand as a template. Once complete, the original nucleotide sequence is restored. | |||
Uvr proteins are necessary to repair damage caused by ultraviolet light in genomes. Mutants of the ''uvr'' genes are very sensitive to killing by UV irradiation and are incapable of removing thymine-thymine and thymine-cystine adducts. | |||
==Components== | ==Components== | ||
Revision as of 23:02, 24 February 2012
General Description
UvrA and UvrB are the first of four enzymes that assist in excision repair, and are both responsible for first scanning DNA for distortions. Once a genome distortion, such as those caused by a thymine dimer or another chemical adduct on a base, is detected by UvrA, UvrA leaves and UvrB proceeds to melt the DNA, creating a bubble around the lesion. UvrB then recruits UvrC. UvrC cleaves the area of the bubble, including the lesion, creating a short, single-stranded DNA segment that is then removed by DNA helicase, UvrD. The gap which results from the excision is filled by DNA polymerase and DNA ligase using the undamaged strand as a template. Once complete, the original nucleotide sequence is restored.
Uvr proteins are necessary to repair damage caused by ultraviolet light in genomes. Mutants of the uvr genes are very sensitive to killing by UV irradiation and are incapable of removing thymine-thymine and thymine-cystine adducts.
Components
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